Unit 6

• Humans use a variety of energy sources, resulting in positive and negative consequences
• Extracting and converting energy resources


  1. How do we extract this fuel source from the ground or what natural process or cycle are we harnessing?

  2. How do we convert this energy into something useful like electricity or liquid fuel or heat?
• Energy sources


  • Advantages (environmental, economic, and human health related benefits)
  • Disadvantages (environmental, economic, and human health related drawbacks)
• Natural Gas


  • Extraction: Often found on top of existing oil deposits, trapped underneath impermeable cap rock. Extracted by drilling through the cap rock and piping it up to the surface. Can also be extracted from sedimentary rock formations like shale through fracking.
  • Conversion: Burned in a power plant to produce electricity, and burned in furnaces to heat buildings.
  • Advantages: Releases far fewer air pollutants like particulates and NOx compared to burning coal or oil. Releases less CO2 per unit than either of these fossil fuels. Can be converted into liquefied natural gas and used as a replacement fuel for gasoline.
  • Disadvantages: Extracting natural gas allows methane to leak out of the wells, which traps far more heat per molecule in the atmosphere than CO2. Extracting it can result in habitat loss when clearing lands to transport the natural gas or bring in drilling equipment. Fracking can result in groundwater contamination with flowback fluid, water depletion from local surface waters and aquifers, and the possibility of increased seismic activity.
• Switching from coal to natural gas fired power plants

  Could be a solution to reduce acid rain (Topic 7.7) because burning natural gas releases less SOx and NOx than burning coal
• Renewable resources


  Energy sources that are easily replenished and will not run out
• Non-renewable resources


  Energy sources that are in a set amount and will eventually run out
• Non-Renewable Energy Sources


  • Fossil Fuels (Coal, Oil, Natural Gas)
• Biomass energy can become non-renewable if not used sustainably, meaning at a rate faster than it can be replaced
• Renewable energy sources are not evenly distributed worldwide, and different regions have access to different resources
• How Energy Use Changes with Industrialization

  Switch from biomass-based energy to fossil fuels and eventually to more advanced resources like nuclear power
• Energy Consumption Graph (US)

  • Coal (big jump in 1883)
  • Natural Gas (increase in 1950s)
  • Nuclear Power (increase post-WW2)
  • Petroleum (consistent increase throughout)
• Factors Affecting Energy Use

  • Price changes
  • Availability
  • Government regulations
  • Global events
• Biomass energy


  Energy generated from organic matter, such as wood, peat, and charcoal
• Characteristics of Biomass Energy

  • Excellent for less developed countries due to ease of access and low cost
  • Can have pollution issues, releasing particulate matter and carbon compounds when burned
  • Not entirely pollution-free, despite being renewable
• Coal


  Acquired through mining, which has significant environmental impacts
• Types of Coal


  • Lignite (low energy content, low sulfur)
  • Bituminous (high energy content, high sulfur)
  • Anthracite (high energy content, low sulfur)
• Bituminous coal is the most commonly used due to its high energy content and large supply
• Bituminous coal is also high in sulfur, making it polluting
• Anthracite coal is low in sulfur, but only available in limited quantities
• Crude oil


  A fossil fuel that can be drilled and pumped from the ground
• Characteristics of Crude Oil


  • Can be converted into various fuel types, but energy conversions are often inefficient due to the second law of thermodynamics
  • Releases carbon compounds when burned, contributing to climate change and pollution
• Fossil Fuels


  Fuels formed from ancient plants and animals, including coal, oil, and natural gas
• Combustion


  A chemical reaction between a fuel and oxygen, releasing energy in the form of heat and light
• Incomplete Combustion


  When combustion is not complete, it can lead to pollution, releasing carbon dioxide, water vapor, and particulate matter
• Cogeneration


  A process that generates electricity and heat simultaneously, increasing efficiency and reducing waste
• Natural Gas


  A fossil fuel extracted through fracking (hydraulic fracturing) from shale rock
• Fracking


  A process that injects water, sand, and chemicals into the ground to release natural gas from shale rock
• Problems with Fracking


  • Earthquakes caused by the injection of fluids
  • Groundwater contamination potential
• Coal-Fired Power Plant


  1. Coal enters the power plant

  2. Coal is burned in a furnace, producing heat

  3. Heat vaporizes water, creating steam

  4. Steam spins a turbine, generating mechanical energy

  5. Mechanical energy is converted to electrical energy by a generator
• Nuclear Power Plant


  1. Uranium 235 undergoes fission, releasing heat

  2. Heat is used to produce steam

  3. Steam spins a turbine, generating mechanical energy

  4. Mechanical energy is converted to electrical energy by a generator
• Containment Structure


  A containment structure is essential at a nuclear power plant to keep radiation inside the reactor
• Radioactive Waste


  High-level radioactive waste must be disposed of, often stored on-site in dry storage casks due to the lack of a safe alternative
• Thermal Pollution


  Thermal pollution occurs when hot water from the reaction is released back into the local reservoir, affecting aquatic organisms and the environment
• Solar Energy


  • Photovoltaic Cells: Capture sunlight and convert it into electric energy through a conductive material
  • Passive Solar Energy: Uses building design and materials to retain heat and reduce energy consumption
• Concerns with Photovoltaic Cells

  • Blocking sunlight from reaching the ground, affecting plant growth and ecosystems
• Thermal Mass


  A type of material that can absorb and release heat. During winter, it can absorb heat from the sun and release it into a building, reducing the need for artificial heating.
• Hydroelectric Power


  Involves the use of dams to harness the energy of moving water. Types include Dam Hydroelectric Power and Wave Hydroelectric Power.
• How Hydroelectric Dams Work

  1. Water from a river or ocean passes through a turbine, causing it to spin

  2. The spinning turbine is connected to a generator, which produces electricity

  3. The electricity is then sent to surrounding neighborhoods and consumers
• Advantages and Disadvantages of Hydroelectric Dams

  • Advantages: No pollution issues, Can prevent flooding, Can provide irrigation and drinking water

  Disadvantages: Can affect fish migration and river ecosystem, Can be expensive to build and maintain